Most batteries are constructed using a container, known as a can, that holds reactive chemicals that drive the battery by electrochemical reactions. The chemicals are usually divided by a separator. An electrolyte fluid facilitates ionic flow between the chemicals and across the separator to develop an electric potential.
Generally, alkaline batteries include a cathode, an anode, a separator, and an electrolytic solution. The cathode is typically formed of an active material (e.g., manganese dioxide), carbon particles, and a binder. The anode can be a gel including an active material (e.g., zinc particles). The separator is usually disposed between the cathode and the anode. The electrolytic solution, which is dispersed throughout the battery, can be a hydroxide solution. Alkaline batteries include the conventional AA, AAA, AAAA, C, and D batteries commonly sold in stores. These conventional alkaline batteries include a cylindrical container containing a central, cylindrical zinc gel anode surrounded by a thin separator, which is in turn surrounded by a ring-shaped cathode.
In the manufacture of alkaline batteries it is common to start with a cylindrical can to which is first added a pelletized cathode material that is in the shape of an annulus. A separator is then placed against the surface of the cathode inside the annulus. The separator may be a preformed cylindrical sheet of, e.g., cellulose material, or the separator may be material that is applied as a liquid and then forms a stable film. A small precharge of electrolyte is then added to wet the separator. The precharge is poured into the annular opening defined by the separator and forms a small pool at the bottom of the can from which it wicks into the separator after a period of time. After the pool has been substantially depleted by the wicking action, the anode material, typically a slurry containing, for example, zinc particles, is added to the opening. Allowing time for sufficient wicking is important so that addition of the anode slurry does not displace the pool and cause spillage of electrolyte over the top of the can.